Steam iron with thermally-operated valve



Dec. 23, 1958 o. P. PRATT STEAM IRON WITH THERMALLY-OPERATED VALVE Filed Feb. 24, 1954 Gol www I N V EN TOR j? Praz?" United States jatent 'IRON WITH THERMLLY-OPERATED VALVE otto P. `Pratt, Elgin, nl., assigner t- McGraw-.Edison Company, Va corporation of Delaware Application February 24, 1'954, Serial N o. 412,238

2.Claiins;. (Cl.i3877) t invention is concerned with axsteam iron, and more 4particularly with aawater. valve for a flash boiler type steam `iron.. t ,t y

In theiash boiler typeizof Asfteamt..iron, water from a `storage tank is metered-into atheatedxlevaporating chambertwher'e it flashes 'into steam substantially instantane Louslyf. Heretoforeiwater often has started .to runrinto the evaporating :chamber` fromwthe. storage tank before lthe evaporating Jchamber has'been-fheated `to aI high` :enough temperatureto cause thewater to flash into steam. When steam ,isgenerated inzevaporating or steam generating 'chambers vwithzan .exc-ess of Water, such `being .the case when water `enters the. chamber` before it has reached lsteas'ming.temperature,1droplets `ofwater arel likely to be carriedout of the iron withthesteam.. Furthermore, after reachingtpropersteaming `temperature `the ironv may be `cooledfoy applicationl to excessively wetwork. Many types of fabrics, such as silk and rayon, are'spottedV by water:drops,. and it-thus will beapparent that it .is highly undesirable forwa-ter 'drops tobe `carried lfrom the viron `with .theisteam.

- v".Aecordingl'y,` it is anvobjectrof Vthis invention to provide a flash boilertype steam iron wherein no `water enters the steam generating chamber until this chamber has reached` the proper temperatureV for generating steam,- 'and then only sso 'long as it is Imaintiain'edfat such temperatures.

.More particularly; itrisl-an object tof-this invention to provide, in `awliash boiler type-steam: iron, `a thermostaticallycontrolled"valveA preventing entrance of water into 'the steam generating chamber except when the steam generatingfchambersis at steam generating temperature.

Afurlther object of this linvention is to provide a Hash boiler type steam iron wherein the soleplate of the iron isused. as part ofthe-.steamgenerating Vchamber and as par-t of .a thermostatic valve allowing entrance of water to'the,steamgeneratingchamber onlywhen said chamber is at steamugenerating.:temperature.

Yet anothenobjecbof this invention is to` provide a ash boilentype steamwir'on-wherein athermostatic valve controlsentrancecof *water to 'thesteam generating chamber, andfzsaid :valve isznotadversely affected by the .presence ofl relatively coolfwater. `ifm-still further object of this invention is to provide, in affltshboiler type steam iron, althermostatic valve for controlling entrancenftwater into. theisteam generating chamber, which valve is afforded a quick `opening action by Contact of the first entering'water with onev of the thermostatic elements.

Otherfand: further objects and `advantages of the present invention will 'be'apparent from the `following description whenttakenin connection with the accompanying drawings wherein:`

Fig. l is a side elevational view of an iron constructed in accordance with theprinciples Vo'f this invention, and with a part thereofbroken away to show the ller tube and its cooperation with the thermostatic valve;

Fig. 2 `is a fragmentary longitudinal sectional View through they iron with the valve in closed position;

Fig. 3 is lafragmentary View similar to a portion of Fig. 2"andshowing the valvein opened position; and

Fig. 4 is a detail view of a part of a valve.

2,865,119* Patented Dec. 23, 1958 Referring -now in greater particularity to the drawings,

having a body portionfincluding a sheet metal case 12 of `moreor less usual design, and a soleplate, 14. A handle 16 `which .preferably is .molded of a thermal Vinsulating Aplastic is suitably affixed to .the top of the casing.12. The handleis provided. withV a. substantially upright filler tube 18 extending through .theforward portion thereof and comprisingta cylindrical tube 20 and a bushing 22 at the upper Vend thereof, said bushing being threaded into the handle.

The bottom endfof the filler tube 18 extendsinto. a reservoir or water storage.tank v24 to which it is brazed or welded as indicated-'at 26. The tank 24 is supported within the body vcasingl-Zat the forward end by a valve structure28 later to be described in detail, and at the rear 'end by a bracketi (not shown). Suitable means is provided for heating the.solep1ate .and this means is illustrated as an electric resistance heating element ,32 of known construction cast inplacein .the soleplate. VTheheating elefment .is controlledxby a. .suitable thermostatic mechanism 34, and the temperature kat which the therm-ostatic mechanism operates is Adetermined by a suitable setter or pointer 36 extendingabove Ythe body casing 12 from beneath the :rear portion vof the ,handle V16. This pointer cooperates'with ,a suitable dial v38 indicating. the various `types of fabrics which..may.be ironed.

The valve structure 28, previously mentioned, extends fromthefront endofthe water storage tank lor reservoir 24 down,intozan'evaporatingor steam generating` chamthereon. Apertures or bores 102extend from the tops of these bossesl'tltl entirely through the soleplate and out the bottom thereof for the passage of steam from the evaporating surface 104.

The valve 28 comprises an externally threadedcylinder 106 extending through suitable openings in the bottom 'of the water tank 'or reservoir 24 and in the sheet metal plate or cover of the steam generating chamber. The cylinder 106 is provided with an integral external collar or ring 108 lying-between thereservoir and steam generating cham-ber, and sealing rings, washers, or gaskets 110 and 112 are interposed between this collar or ring and the reservoir and steam generating chamber. A nut 114 threaded on the top of the cylinder 106 clamps the bottom of the 4reservoir against the lsealing ring, 110 and the collar 108, and a nut 116 threaded on the bottom end of 'the cylinder 106 clamps the cover or plate 90 against the sealing ring 112 and collar 108.- It will be noted that the valve 28.is aligned with the opening through the ller tube 18 so that a wrench can be slipped through the-,filler tube to'tighten the nut after assembly.

An opening 'or bore 118 extends axiallvthrough the cylinder 106, and is beveled or flared outwardly at the ends thereof so as to form a lower valve seat `120. The bevel at the-top facilitates entrance of water into the valve when the water level in the reservoir is low, and it=further yaffords a symmetrical `construction simplifying initial assembly in that the valve may be inserted with eithery end up, and providing prolonged valve life in that the cylinder `106 can be inverted if the valve seat 120 becomes worn.

The soleplate 14 preferably is made of aluminum or aluminum alloy. A bowed strip 122 of material having a coeicient of expansion lower than aluminum is positioned in the steam generating chamber with the ends of the strip affixed to the evaporating surface 104 of the soleplate by fasteners 124 which may be screws, or any other suitable fasteners. A split, threaded stud 126 extends through the bowed strip and is spot welded thereto as indicated at 128 in Fig. 4. The legs of the split stud are spread slightly apart so that the threads on the stud will frictionally grip the internal thread's 130 of a valve closure member 132 having a beveled surface 134 engageable with the valve seat 120 to close the valve. The valve closure member 132 is provided with a stem 136, and the top of this stem is provided with a slot 138 for a screw driver adjustment of the valve closure member.

The valve closure member 132 is adjusted with a screw driver extending through the filler tube 1S. Preferably it is so adjusted that the valve begins to open at 250 F. Then at lower temperatures member 122 will buckle slightly, and the valve is closed as indicated in Fig. 2. When the iron heats up, the aluminum soleplate expands at a faster rate than the strip 122. This tends to pull the ends of the strip away from one another, and thus the strip is partially flattened out. As the strip flattens, it withdraws the valve closure member 132 from the valve seat 120 to allow water to pass from the reservoir into the steam generating chamber. The water in the reservoir being below 212 F. is cooler than the soleplate, and when it enters the steam generating chamber it encounters the strip 122 and cools the strip slightly. This action contracts the strip somewhat and effects a more rapid opening of the valve.

The distance that the valve member 132 is withdrawn from its seated position depends on the temperature of the iron compared to the opening temperature, and whether or not there is water flowing. So long as the opening is so small that the seating parts 120 and 134 provide the principle control of the ow, the rate of ow will increase with the temperature of the soleplate. At larger Aseparations the llow rate will be determined principally by the cylindrical bore 118 and stem 136, and will not increase materially with further rise of soleplate temperature. I prefer that the soleplate and steam chamber operate at about 325 for steam ironing of all fabrics, and for such operation I prefer that valve member 132 be adjusted to begin opening when the soleplate rises to about 250 F. and that the maximum rate of water flow be obtained with the soleplate at about 275 to 300 F. Of course, substantially the same maximum ow will be obtained at all higher temperatures. The valve is shown open in Fig. 3.

Alternatively steam ironing may be done with various soleplate and steam chamber temperatures. For such use the valve member 132 may be adjusted to provide a small water flow at some low temperature for fabrics such as nylon, acetate or rayon. At higher temperatures for fabrics such as wool, linen and cotton, the valve will open farther to provide a greater ow to utilize the higher steam generating capacity of the steam chamber at the higher temperature. For example, for such operation, water may begin flowing slowly when the soleplate has risen to 225 F., and may increase its ow rate gradually and provide maximum rate at a soleplate temperature of 350 to 375 F. The temperature difference between the temperature for initial opening and the minimum temperature for maximum flow will depend on the movement required of valve member 132, the specific materials of the soleplate and the strip 122, and the angle that strip 122 makes with the soleplate.

It previously has been noted that the soleplate 14 preferably is made of aluminum or aluminum alloy. This imparts a high coelicient of expansion to the soleplate,

and it is comparatively easy to select a material for the.

strip 122 that will have a lower coecient of expansion. Preferably, however, the strip is made of any of several commercially available alloys of nickel and iron. One

such alloy is available under a number of dilerent trademarks and is composed of approximately 58% iron. This material has a coefficient of expansion about lfs that ofaluminum up to 600 or 700 F. An alloy of about 36% nickel and64% iron, sold under the trademarks Invar and Nilvar, has an even lower coeicient of expansion at temperatures `below 350 F. In

this temperature range, a coecient of expansion of this l material is about 4% that of aluminum. This temperature range is generally satisfactory inasmuch as flash type steam irons are usually operated at about 325 F. Furthermore, this alloy is not damaged at exposure to higher temperatures, such as 550 F., at which the iron may be used when operated dry.

It is obvious that the steam iron herein disclosed satisfies the objects of the invention. Water cannot enter the steam generating chamber from the reservoir unless the steam generating chamber is at steaming temperature. The thermostat valve is not subject to improper operation due to the cooling affect of the incoming Water, but actually is operated more quickly as one part of the thermostat is contacted by the cool water. The degree to which the valve is opened can be determined in accordance with the operating temperature of the iron, and the rate of steam generation thereby made commensurate with the operating temperature of the iron and the requirements of the particular fabric being ironed. Since the soleplate is used as a part of the thermostat, the principal response of the valve necessarily is to the temperature of the soleplate itself. The valve used in thisA steam iron readily can be assembled and adjusted through the ller tube.

It will be understood that the particular structure herein shown and described is for illustrative purposes only. Various changes can be made and form a part of my invention insofar as they fall within the spirit and scope of the appended claims.

I claim:

1. A steam iron comprising a sole plate constituting one element of a thermostat and formed of a material having a relatively high coefficient of expansion, said sole plate having a recess therein forming a steam generating chamber with an evaporating base, means for heating the sole plate, means providing a water reservoir, a cover plate for the steam generating chamber, means providing a passage from the water reservoir through the cover plate and to the steam generating chamber, an upwardly bowed strip disposed in said recess and constituting the second thermostat element of a material having a relatively low coeflicient of expansion and with the ends thereof secured directly to the evaporating base of the sole plate and confined within the steam .generating chamber, and a valve member carried by the central portion of the bowed portion of said strip and positioned to cooperate with said passage to control the flow of water through said passage and said strip being at least partially disposed in the path of water owing from the passage when the valve member is in open position whereby the strip is cooled to resist reclosing and chattering of the valves.

2. A steam iron as claimed in claim l, wherein the valve member is mounted on the bowed strip by means of a split threaded stud extending through the bowed strip and into an internally threaded recess in the valve member whereby the position of the valve member with respect to the bowed strip may be adjusted.

References Cited in the file of this patent UNITED STATES PATENTS 1,948,008 Rossman Feb. 20, 1934 2,137,876 Hudson Nov. 22, 1938 2,317,706 Woodman Apr. 27, 1943 2,584,924 Reingruber et al. Feb. 5, 1952 2,596,684 Hedenkamp May 13, 1952 

